The objective of this proposal is to covalently immobilize an all-carbon nanoparticle that is an excellent photosensitizer (PS) onto biologically inert polymeric backbones for the photodynamic inactivation of pathogens in blood products. The polymers will then be placed in a permeable cartridge and fixed into a flow-through reactor. After filling the reactor with the blood product, the fluid will be circulated and the photocatalyst illuminated with laser light. The illuminated PS catalyzes the formation of singlet oxygen, 1O2*, a reactive species of oxygen that will inactivate pathogens in the blood product. The decontaminated blood product is then simply removed from the reactor, leaving the C60-modified polymer behind. Three types of polymeric backbones will be investigated: 1) hydrophobic polymer, 2) polycationic polymer, 3) non-ionic hydrophilic polymer. The synthetic steps to modify the polymers with C60 start from commercially available polymers and are simple literature procedures. After photocatalyst synthesis and construction of the reactor, the pathogen inactivation system will be evaluated in a series of in vitro experiments to determine the optimal blood product decontamination applications of the new system. Several advantages are expected over conventional homogeneous PS such as methylene blue: 1) there is no post-treatment toxicity because the photocatalyst is heterogeneous and integrated into the reactor structure and upon completion of treatment, the blood product is simply removed from the reactor leaving the catalyst behind, 2) enhanced selectivity of pathogen inactivation is expected due to the polymeric backbone's tunable affinity relative to damage to blood components 3) the nanoparticle PS that will be used has a very high singlet oxygen quantum yield, higher than conventional PS The vision of this project is to introduce a novel, economical system to the blood product market for the inactivation of pathogens in blood products.